Heavy equipment, such as load-haul-dump machines (LHDs), wheel loaders, carry dozers, etc., are used during an excavation process to scoop up loose material from a pile at a first location (e.g., within a mine tunnel), to haul the material to a second location (e.g., to a crusher), and to dump the material. A productivity of the excavation process can be affected by an efficiency of each machine during every excavation cycle. In particular, the efficiency of each machine increases when the machine's tool (e.g., a bucket) is fully loaded with material at the pile within a short amount of time, hauled via a direct path to the second location, and quickly dumped.
The efficiency of a machine can be affected by accuracy in movements of the machine's tool linkage system. In particular, when a machine has full movement capacity, and the movements precisely correspond with operator and/or autonomous control commands, the machine may perform at a higher level. The movement capacity and precision may be ensured by periodic calibration of the tool linkage system.
An exemplary calibration system is disclosed in U.S. Pat. No. 6,615,114 of Skiba et al. that issued on Sep. 2, 2003 (“the '114 patent”). The calibration system includes a position sensor coupled to a lift cylinder of a front-end loader, and an electronic control module (ECM) operatively coupled to the position sensor. The position sensor senses the position of a piston inside the lift cylinder, and generates a corresponding position signal directed to the ECM. During a calibration process, the ECM generates and transmits a command signal to fully extend the lift cylinder. As the lift cylinder is extending, the movement of the piston is monitored by the position sensor. The ECM differentiates the signals generated by the position sensor during cylinder extension to detect when a velocity of the cylinder is zero. Once a signal representative of the cylinder being in a fully extended position is generated by the position sensor (i.e., when the cylinder velocity is zero), the ECM stores the value of the position signal in memory. The ECM then uses this value as a fully extended calibration factor. The ECM also performs a similar calibration process with respect to moving the lift cylinder to its fully retracted position.
Although the calibration system of the '114 patent may be helpful in calibrating a position sensor associated with a lift cylinder, it may lack applicability to more complicated machines, where multiple actuators interact with each other in a dependent manner.
The disclosed excavation system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.